From a Lutheran perspective; both. Why? Because Scripture referres to it both ways.
Indeed. And from an Orthodox perspective, we would say that it is the Body and Blood of our Lord, but retaining the outward appearance and other perceptual attributes of bread and wine under normal conditions for our comfort (but occasionally, God allows someone to see the Eucharist as the true flesh and blood of our Lord, where this is beneficial to their salvation: there was a Muslim who saw this, and immediately summoned guards, for fear that the Orthodox Christians were devouring someone, but when they returned to the parish, he saw the Eucharist in the form of bread and wine, and seeing this, he converted. And of course, since conversion to Christianity is punishable by death in the Muslim lands, he won the crown of martyrdom as soon as word got out that he had become a Nasrani (Christian) and became a glorified saint in the Orthodox church.
Now, in Orthodoxy, we are reticent to say exactly how this divine mystery actually works, since God is omnipotent and the inner workings of the Eucharist are less important than what they provide us, and like Lutherans, prefer a simple explanation, and for this reason you and I have argued against the complex Scholastic model of the Eucharist taught by Thomas Aquinas which depends upon Aristotelian categories. The Lutheran and Orthodox approaches have the benefit of a greater simplicity and do not depend upon the complex Scholastic systematic theology (which in turn motivated Calvinists to pursue even more complex models of systematic theology.*
At any rate, the argument that the Eucharist can only be bread and wine or the Body and Blood of our Lord is an obvious false dichotomy, one of a great many false dichotomies that we encounter in the belief systems of Memorialists and Zwinglians (another one being the false dichotomy that everything that does not agree with their particular Radical Reformation or Restorationist theology is somehow a product of Roman Catholicism, despite the fact that as Martin Luther realized when he studied the fascinating Ethiopian Tewahedo Orthodox Church and concluded that it was an example of a doctrinally orthodox church that had always been entirely outside the control of the Roman Pope (something which is also true of the Church of the East, the Coptic Orthodox Church, the Syriac Orthodox Church, the Armenian Apostolic Church, the Mar Thoma Christians of India, and the Eastern Orthodox Communion; additionally the Maronites were an independent Monothelite church which happened to venerate several Roman bishops including most likely Honorius I, and which separated from the Syriac Orthodox over the issue of Monothelitism, and this enthusiasm for Rome caused them to form an alliance with the Crusaders when the latter passed through Lebanon which led to their integration into the Roman church.**
* I would argue that the Summa is relatively easy to comprehend compared to the ponderous Church Dogmatics of Karl Barth, which for all of their immense size are I would say superfluous in that Calvin’s institutes are more compact and more faithful to the Patristic tradition, but not faithful enough, since Calvin presumed to pick and choose which aspects of the theology of the Early Church he liked and would retain, which is ironic considering that later Calvinist theologians coined the term consensus patrum, yet the Institutes are not compliant with the consensus patrum insofar as they are Iconoclastic, Monergist, and only narrowly avoid Nestorianism (insofar as Calvin only reluctantly conceded that the Blessed Virgin Mary was correctly referred to as Theotokos).
** One could argue that in terms of safety, this was a good move, considering that, as far as cannibalism is concerned, the only large scale incidence of actual cannibalism in Christianity I am aware of is when the Crusaders in the First Crusade ran out of provisions while passing through what is now Eastern Turkey and Syria, and according to the Antiochian Orthodox and Syriac Orthodox Christians from the region, resorted to cannibalism, specifically targeting the local Orthodox Christian communities due to the lack of resistance they presented to the crusaders. These incidents, and other atrocities committed against the Eastern Orthodox and the Oriental Orthodox during the Crusades had the effect of cementing the schism that had existed between the Greek Orthodox Church of Constantinople and the Roman Catholic Church since 1054, and between the Antiochian Orthodox Church and the Roman Catholic Church since 1078, by giving the laity of these churches a reason to resent the Roman Catholic Church; prior to the Crusades, the Schism was essentially an issue of ecclesiastical politics with almost no appreciable impact on the lives of the Eastern Orthodox laity.
The Crusades also ironically resulted in some degree of reconciliation between the Eastern and Oriental Orthodox, who increasingly found themselves facing common enemies in the form of Islam and now Roman Catholicism, which made put historical record of the violent persecution inflicted on the Syriac Orthodox during the reign of Emperor Justinian and his successors five centuries previously into perspective, as a distant memory with little relevance to the current situation. Thus we can understand the process of reconciliation, which resulted in such occurrences as the attempted merger of the Coptic Orthodox Church of Alexandria and Greek Orthodox Church of Alexandria in the 19th century. This was of course blocked, on the basis of
divide et impera, by the Albanian Khedives (viceregal princes) who had seized power from the Ottoman Sultan in Egypt (although shrewdly still behaved as though they were his vassals, affording the Sultan every nominal courtesy, so as to avoid adding a personal insult to the real injury they had inflicted), since obviously a unified Egyptian Orthodox Church would pose more of a threat to their reign. Likewise a later Khedive also acted to prevent the Ethiopian Orthodox Church from becoming an independent church, free from Coptic Orthodox supervision, by refusing a request from the Ethiopian Emperor to increase the number of bishops to six (which under Coptic and Ethiopian canon law would have made the Ethiopian Orthodox Church ecclesiastically independent (autocephalous, to use the technical ecclesiological terminology), for similar reasons, although this would later happen in the 20th century during the reign of the martyred Emperor Haile Selassie.